New readme, now with text

README.md

 # parallel_worlds
 
+This is the repository for the "parallel worlds" OpenCL example originally
+published in c't 26/2014.
+The final program takes images from a camera -- or, if none can be found,
+a stored input image (preview.png). It then transforms the image into a grey
+image, from which the edges are extracted using a Sobel operator. The result
+is then used to enhance the edges found in the image.
+